Euromuse.net
http://www.euromuse.net/en/home/
Portal providing information on major exhibitions in European museums. Updated by the host museum, the database is searchable by date, by topic or by country. Each museum's information is available in the native language and in English.

Network of European Museum Organizations
https://www.ne-mo.org/
List of Network members by country.

Museum Directory on Wikipedia
http://en.wikipedia.org/wiki/List_of_museums

Art Museums Worldwide
http://www.artcyclopedia.com/museums.html

European Network of Science Centres and Museums
http://www.ecsite.eu/members/directory
Searchable members directory.

The Association for Science and Discovery Centres (United Kingdom)
http://sciencecentres.org.uk/

Irish Science Centres Association Network (Ireland)
http://www.iscan.ie/

Austrian Science Center Network (Austria)
http://www.science-center-net.at/

Nordisk Science Center Forbund (Denmark)
http://www.nordicscience.net/

Libraries and Archives Directory
http://europa.eu/publications/libraries-archives/index_en.htm#40
A “directory” of EU institutions.

National Archives Directory
http://libguides.usc.edu/content.php?pid=22394&sid=1211712
A USC Libraries’ guide which links to the official web sites of national archives around the world.

List of Archives
http://en.wikipedia.org/wiki/List_of_archives
Wikipedia listing of national archives.

Historical Archives of the European Union
http://vlib.iue.it/hist-eur-integration/Archives.html
Websites of the National or State Archives of the 25 Member States of the European Union.

Archives Portal Europe
https://www.archivesportaleurope.net/
Provides access to information on archival material from different European countries as well as information on archival institutions throughout the continent.

National Archives of the United Kingdom
http://www.nationalarchives.gov.uk/

ArchiveGrid
http://beta.worldcat.org/archivegrid/
A database for locating special collections worldwide. Search for family and corporate histories, personal papers, and historical records. Over 2,500 libraries, museums, and archives worldwide contribute collection descriptions.

Archive Finder
https://research.lib.buffalo.edu/archive-finder
A current directory describing over 206,200 collections of primary source material housed in thousands of repositories across the US, UK, and Ireland.

Oral History Online
http://historymatters.gmu.edu/mse/oral/online.html
Provides in-depth indexing to more than 2,700 collections of oral history in English from around the world, including many full-text transcripts, audio, and video.

WorldCat
https://research.lib.buffalo.edu/WorldCat
Enter a subject term and limit your search to "Archival Materials". Or use subject keywords such as sources or diaries or interviews or pamphlets or correspondence or personal narratives or archives.